Absolutely! When you are a personal trainer, you might not want your clients to be able to create their own workout plans, since that is what they are paying YOU for. You could choose to disable the entire Workout app (read more about that here). but that also restricts them from assigning a workout plan to themselves. This is something you might want to allow, when you have certain "club plans" that your clients can choose from.
That is why we've developed an option that allows you to disable your client's ability to create workout plans. You find this option in the system settings under portal content. Just uncheck the box "clients can create workout plans," save the settings and you're ready to go!